Formerly Drafting and Design

Co2 Dragster Derby

These are the Co2 Dragster designs created by the drafting students at Bonneville High:

The following video is of the Co2 Dragters at Bonneville High:

These are Dragsters that were printed on the 3D Printer at Fremont and designed by the students in the Advanced Mechancial and CAD Drafting Courses. They were raced on 1/12/2011 at the first bi-annual Co2 Dragster races.

Announcing the First Bi-Annual Co2 Dragster Derby for student in CAD and Advanced Mechanical Courses (Architecture class students can participate as well, if they have had the CAD class first).

CO2

DRAGSTER DESIGN AND

CONSTRUCTION

Weber School District Official CO2 Dragster Project Guidelines

CO2 Dragster Project

Each Student is required to Design, Sketch, Model and produce Dimensioned Drawing and a Rendered View. Creating a physical model and participating in the drag race is Optional and non-participation will not affect the grade, provided all of the drawings completed.

Materials:

Parts List Costs Totals

2 x front wheels (#19-1015) $0.30 each $0.60

2 x rear slicks (#19-1016) $0.30 each $0.60

1 x CO2 cartridge (#19-1018) $0.50 each $0.50

2 x steel axles (#19-1023) $0.25 each $0.50

4 x brass washers (#19-1021) $0.10 each $0.40

2 x screw eyes (#19-1024) $0.10 each $0.20

1 x plastic straw (#19-1022) $0.10 each $0.10

1 x 3D PVC Model of your dragster design Not to exceed $20.00

Total Costs Less than$25.00

Addition design aids: sandpaper, paint, and stickers

Basic How-To:

1) Draw a sketch of your design idea. Begin your preliminary design process by making several thumbnail sketches or possible car designs on a layout sheet

2) Choose the design features that you think will make the best overall car and neatly sketch the side and top views.

3) Do a final drawing which will be an exact drawing showing the shape and exact detail so that another student can build/draw the exact same design.

Please Note:

Your car need to be a less than 8” long or less for the main body. You can design addition features like fenders, fines, and air foils that can be glued on later if you wish. The shape cannot be less that 3/8” thick between the front and rear of the car. The axles must be drilled 3/8” from the bottom of the body but can be placed any distance from the front or rear of the car.

Concept Sketch Dimensioned Drawing

4) Begin to shape your design with first a coarse profile then refine you design has you go. Make sure the corners are rounded. Try to keep each side symmetrical. This will help maintain good balance.

5) Your 3D model can be sanded and painted. Paint that does work is all purpose spray paint or acrylic. Be sure and apply a primer coat first. You can use shellac or clear coats to give your carC a shine.

7) Measure the straw & cut to length. The straw should not stick out from the sides of your car. Now insert the straws in the axle holes. (Axle hole should be 4mm or 0.15748 inches).

8) Put the axles into the straws in the axle holes.

9) Now put the washer on the axles and attach the wheels. Make sure there is not a lot of friction. The wheels should move freely.

10) Set you car on a desktop and locate the best spot for the screw eyes. They need to be located on the centerline of the bottom of your car and on the lowest points near the front and the back of your car. Twist in the screw eyes then place your car on the desktop again to see if they rub against the top. Twist them further in if they do. All four wheels should be touching your table.

Finishing Touches:

Lubricants help to reduce the friction on the axles. Rub pencil lead (graphite) on your axles to help them turn with less friction. Sand down any burrs on the surface of your plastic wheels. (Do not use liquid lubricant).

Design Criteria:

The criteria listed below must be followed closely. Cars that are not built within these measurements may not be permitted to race:

DESIGN SPECIFICATIONS

Maximum

Minimum

AXLES (length)

2 3/4″

1 5/8″

AXLE HOLE(distance from either end of body)

4″

3/8″

DRAGSTER BODY LENGTH

8″

6″

DRAGSTER BODY HEIGHT (at rear with wheels)

3″

2 1/8″

DRAGSTER BODY WIDTH (at front and rear axles)

1 5/8″

1 3/8″

DRAGSTER BODY WEIGHT (assembled)

30g

170g

WHEELBASE (distance between axles)

7 5/8″

4 1/8″

POWERPLANT HOUSING THICKNESS

***********

1/8″

POWERPLANT DEPTH

2″

2″

AXLE HOLE ( FROM BOTTOM OF CAR)

1/2″

3/8″

SCREW EYES (DISTANCE APART)

7 5/8″

4 1/8″

Optional Values (using these values will increase the cost of the dragster)

Additional length of up to 12” can be accomplished with separate elements glued on to the body with ABS cement.

Notes for Students

(we will be using the 3D printer to create the cars)

THUMBNAIL SKETCHING

Now is the time to get some of those race-car design ideas — undoubtedly floating around in your head — on paper. The best way to start is with concept sketches, also known as thumbnail sketches. Thumbnails are small, quick sketches used by engineers and designers to rapidly communicate ideas. They should not be detailed or even carefully done. Be sure to experiment with different ideas and be as creative as possible.

DESIGN SKETCHING

On a clean sheet of paper, sketch your favourite design from the thumbnail sketches on a larger scale with more detail. Draw the top and side views. Make light projection lines from one view to the other to help you locate axle holes and other features of your design. Show the location of hidden details (such as the cartridge hole) by using dashed lines. Check the specification. Look at your design sketch to see how each spec applies to your design. You may find it necessary to take notes or even change your design.

WORKING DRAWINGS

The working drawing is a precise, 1:1 scale drawing that describes your car and its features. Working drawings should have top and side, or profile, views. An accurate working drawing is important for two reasons: 1) A copy of the working drawing serves as a template for rough-cutting your car blank. 2) You may be required to submit your working drawing. It could be part of your grade or even be scored for competition points (ask your teacher about this). Be sure to refer to the specifications sheet as you go.

Create axle holes of 4mm in diameter (0.15748 inches). (plan to alter these holes to meet the needs of your axle before printing in 3D).

If your design calls for a hollowed-out body, a high-speed rotary multi-tool works. the less PVC material in the design the lower the cost. Try not to rely on power tools to correct a poor design.

PAINTING YOUR CAR BODY

As in the fine shaping stage, extra patience and effort put into the finishing stage can pay big dividends.

Be aware that using several coats of paint can add weight to your car.

1. Make up a handle and hanger. Slightly sand off the edges at one end and drill a hole in the other.

2. Insert the handle into the power plant housing of the car body so that the timber jams slightly against the sides of the power plant hole. Enough to hold it on the handle when it is hanging down. This makes a very convenient handle for turning the body to paint it from all angles and you can hang it from a nail over a drip container while the paint dries.

3. Apply undercoat and sand between coats. You can dip the car body into a deep tall vessel, such as an old vase, filled with the paint and let it hang to dry

4. Use a spray can or airbrush to apply paint to the body. Spray light coats and wait several minutes between coats to allow the paint to dry.

Final Assembly: Mounting Wheels and hardware

Don’t overlook the importance of this stage. A huge factor in race performance is how smoothly the car rolls down the raceway. Some meticulously shaped cars have failed to finish races because of improperly installed hardware.

1. Gather your hardwar: two axles, two straw bearings, four wheels, four washers, and two screweyes. Depending on the configuration of the car body, different hardware might be required. Shell cars (with internal wheels) often require wheel spacers and clips to affix teh axles to the car body.